Wife never had any sleep complaints, sleep quality WORSE with machine. ONLY reason she uses it is fear of future stroke/heart problems. She's used it for 4 months.
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I suspect/fear those 3 or 4 large O2 desaturations are medically significant. I think the clearly corresponding heart rate increases are her body's response to low O2 (or high CO2), and represent exactly the stress that contributes to future problems.
Questions:
1) Is that true? Why/why not?
2) Can I expect sleep doc to take one look and say "We gotta fix that." If not, then what?
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I suspect/fear the machine isn't really doing the job. APAP range is 4-20. I would hope the machine would be maxed out at 20 when she's in trouble - but it's not. OAs and Hyps are somewhat clustered during low O2 events, but it doesn't detect enough to get the pressure up enough. On the other hand, I suspect it detects too many events when she's first falling asleep and O2 levels are fine.
Questions:
3) Is our expectation that the machine will fix this (or be maxed out trying) appropriate?
4) Are there machine tunings (or other machines) that might help combat those low O2 events?
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Thanks for any insights you can offer!
Jim
Long version:
Background: My wife has never had any complaints about sleeping, but snored loudly and I've frequently heard apneic events. She doesn't recall ever waking up from one. She reported to her doctor, did home sleep study ->AHI 34 (BMI 27). PSG and CPAP titration at sleep center -> AHI 28, recommended pressure 11cm. Dr prescribed APAP machine, min 4 max 20cm which she's been using with an AirFit P10 nasal pillow and 100% compliance for ~4 months. 30 day AHI average is 8.8. She tries to not sleep on her back, and mostly sleeps on her side.
She very strongly dislikes the machine and perceives no immediate benefit (since she had no sleep complaints in the first place). She reports her sleep quality is reduced by having to use the machine. But she uses it religiously because she's been told of correlation of untreated apnea with increased risk of heart problems and stroke. That is very scary for her (and keeps her from throwing the machine out the window).
We got the oximeter 6 weeks ago and used it alongside the Dreamstation for a few weeks until the patterns were clear. I wore it for several nights after that, and saw pretty normal results (unlike hers). (I have no known significant apneas.)
OK - now for the questions! My understanding (please correct if wrong!) is that sleep apnea has two primary negative effects: 1) Interfering with sleep quality thru arousals or near-arousals; 2) Stress on the body (suspiciously correlated with heart and stroke problems) due to decreased blood O2 and increased CO2 from reduced breathing volume.
OXYGEN LEVELS
For my wife, 1) doesn't seem to be an issue, and certainly doesn't justify putting up with the machine. So we come to 2). Enter the oximeter data. (Note that we haven't calibrated the oximeter against a standard yet, but the magnitude of the O2 drops puts this way outside a calibration issue. And I think the high correlation of heart rate increase is further evidence that the events are real. Discussion is of course welcome.)
Since a common threshold for concern in O2 saturation level is 88%, and given that my wife's concern is for long term health, the fact that her level drops into the 70s for 5-20 minutes at a time a few times a night (while on the machine!) seems like a real cause for concern. Is that correct? Why/why not? Can I expect that showing her sleep doc that data will get him to take it seriously? And if not should we be concerned anyway?
The oximeter consistently shows a marked increase in heart rate during the O2 desaturation periods. Is it accurate to say this reflects the body's reaction of trying to pump more of that O2-poor blood so tissue doesn't suffer? And is the mechanism of that the release of stress hormones (or something) that is exactly the long term contributor to the heart/stroke health problems she fears? I'm really looking for an accurate understanding here.
Side question: Are those desaturation events likely during REM sleep? We don't have an EEG (yet), and so can't be certain of sleep stage, though the timings are plausibly REM. But with overall relaxation/paralysis during REM, might that exacerbate airway restriction and thus contribute to the problem? Are there mechanisms other than REM sleep that might explain the periodic O2 drops (and associated reduced breath volume)?
MACHINE CONCERNS
Starting on the plus side: The machine is clearly working. Her very frequent loud snoring is completely gone with the machine on. (Nice, but that's not what we're concerned about.) The oximeter baseline data also shows it's helping, and that is a good thing.
During the first maybe 20 minutes after going to sleep, the machine records enough events (mostly Hyps) to get her rolling AHI up to 10+ - although her O2 levels stay normal. Many of these look like periodic breathing, and might be just at the ragged edge of the machine's detection thresholds. I feel the machine is over-reporting here and making things look worse than they are to those who only look at AHI. Is that over-reporting interpretation justified?
When the machine was set for max pressure of 20 (it's down to 15 for reasons unclear to us), we never saw pressure above 15 (usually below 13). It looks like the machine isn't even trying to provide enough pressure to avoid the low O2 events. Looking for patterns over many days of data, there are more OA and Hs during the low O2 events, but it's not enough for the machine to figure out she's in trouble. So here it's arguably under-reporting apnea events and ignoring low breathing.
It seems like OA events result in more rapid pressure increases than Hyps. Does anyone with the $800 (!?) oximeter add-on notice that extended low O2 readings make it crank up the pressure even more/faster?
Looking at both breath-by-breath flow data and "minute ventilation" it's clear she's not getting nearly as much air during the low O2 events as during more normal times. So the real question is: Is it realistic to expect this "gold standard" therapy machine to actually keep her O2 levels close to normal?
LEAKS
While the machine reports only infrequent "large leaks", there are smaller leaks as the pressure increases. She breathes almost exclusively thru her nose, and pretty reliably keeps her mouth closed. But when the pressure is above maybe 10, it blows her lips apart for a noticeable leak. Leaks of 20-30 are common at these times, with 40 occasionally. A chin strap helps a little (to our surprise), but adds to the overall discomfort.
She tried the 3M micro pore tape once, with marginal improvement. We have some Somnifix strips on order.
Since the pressure usually gets up to 10-13 during the low O2 events, there is usually some leakage. The breath amplitude shown in the flow data is always lower at those times. One interpretation is that she's just breathing less - airway restriction or something. Another is that the machine's flow reporting accuracy is compromised a little due to the leaks. The question here is whether there's any observed history with the Dreamstation (500X110) of reduced flow report accuracy (actually reduced breath volume) with leaks in the 20-30 l/min range.
A concern if we did get the machine to provide substantially more pressure is that the parted lip leaks would become even more of a problem. A full face mask is the obvious answer to that, but stroke fears or not, there's serious question whether she'd accept that (for more than a few nights of testing). No questions here, just - ugh.
If anybody's still here, thanks for sticking it out. And again, any insights would be greatly appreciated.
Jim
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